Paperboard-based container

Abstract

A packaging container blank (100) is disclosed The blank comprises an inside heat sealable layer and a plurality of top-closure sub-panels, including: a first top-closure sub-panel (130) comprising a first top-fin panel (180); a second top-closure sub-panel (132) neighbouring the first top-closure sub-panel and comprising a second top-fin panel (182); and a third top-closure sub-panel (134) neighbouring the second top-closure sub-panel and comprising a third top-fin panel (184). The second top-fin panel comprise a gable crease line (183) extending across the second top-fin panel between a top edge (103) and a top-fin crease line (162), which gable crease line partitions the top-fin panel into a first top-fin panel section and a second top-fin panel section. The second top-fin panel (182) has been treated to reduce its sealing strength.

Description

[0001] PAPERBOARD-BASED CONTAINER

[0002] Field of the invention

[0003] The present invention relates to a method of producing a gable-top paper or paperboard based packaging container. In particular, the present invention relates to a method of producing an easy opening gable-top packaging container having a gable closure, i.e. a gable-top packaging container that is designed to be opened by pushing open and pulling out a gusset panel of the gable-top to form a pouring spout.

[0004] The present invention also relates to a blank for producing an easy opening gable-top paper or paperboard based packaging container and to a packaging container produced from such a blank.

[0005] Background

[0006] Gable top packaging containers, also known as cartons, are commonly used to distribute pourable products, e.g. liquid consumable products, e.g. dairy products, such as milk, or fruit juices.

[0007] A gable top packaging container is produced from a laminate packaging material, which typically comprises a multi-ply paper or paperboard sheet on which is laminated one or a plurality of layers for holding the pourable product and / or prevent migration of air and flavour degrading substances through the paperboard. A layer may typically comprise a polyethylene or an aluminium layer.

[0008] The laminate packaging material also typically comprises an inner and an outer heat sealable layer, e.g. made from a thermoplastic polymer.

[0009] In production of the packaging container, the laminate packaging material may be cut to form blanks, which may be folded, filled and sealed to form the packaging container.

[0010] To facilitate folding of the blank, the blank normally comprises crease lines. As is known in the art, a crease line is an embossed or impressed depression on one side of the paperboard with a corresponding raised ridge or welt on the other side forming a line along which the paperboard is structurally weakened and along which the paperboard will bend or fold in a controlled manner when pressure is applied.

[0011] Sealing of the packaging container is typically effectuated by heat seat sealing adjoining heat sealable layers of folded panel sections so that they fuse to form impermeable seams.

[0012] Generally, it is advantageous that the seams thus formed are as strong as possible. However, in gable-top packaging containers designed to be opened by pushing open and pulling out gable panels to form a pouring spout, too-a-strong top seal may make it difficult for a consumer to open the packaging container without compromising the structural integrity of the laminate packaging material. In particular, if the top seal is too strong, the laminate packaging material may easily de-laminate or partially de-laminate during a first opening. In other words, the opening may happen within the bulk layer, or paperboard layer of the laminate packaging material. This causes fibers to be apparent after opening and the repeated use of the packaging container causes moisture to enter the container which compromises the integrity of the container.

[0013] With the above challenges in mind, the present disclosure seeks to bring forward a new method of producing a gable-top packaging container allowing easy opening.

[0014] Summary of the invention

[0015] The present invention is defined by the appended claims and in the following:

[0016] With the abovementioned challenges and known solutions in mind, and according to a first example aspect, the present disclosure provides a packaging container blank made from a laminate packaging material comprising an inside heat sealable layer and comprising a plurality of top-closure sub-panels, the blank comprising: a first top-closure sub-panel comprising a first top-fin panel; a second top-closure sub-panel neighbouring the first top-closure subpanel and comprising a second top-fin panel; and a third top-closure sub-panel neighbouring the second top-closure subpanel and comprising a third top-fin panel, the second top-fin panel comprising a gable crease line extending across the second top-fin panel between a top edge of the second top-closure sub-panel and a top-fin crease line of the second top-closure sub-panel, which gable crease line partitions the top-fin panel into a first top-fin panel section and a second top-fin panel section; the first top-fin panel section being configured to be sealingly attached to the first top-fin panel during top-sealing of the container; the second top-fin panel section being configured to be sealingly attached to the third top-fin panel during top-sealing of the container; and the first top-fin panel section and the second top-fin panel section being configured to be separated from the first top-fin panel and the third top-fin panel, respectively, during opening of the container, providing a pouring spout.

[0017] The second top-fin panel comprises a first sub-region extending transversally across the blank crossing the gable crease line, in which first sub-region the inside heat sealable layer has been treated to reduce its sealing strength; wherein the treatment of the first sub-region on the second top-fin panel is the addition of a layer of an adhesive material comprising a thermosealable matrix and a dispersed phase. In other words, the adhesive material comprises a dispersed phase in a thermosealable matrix.

[0018] In an embodiment, the sealing strength may be a heat-sealing strength. In an embodiment, the surface area of the first sub-region covers at least 80% of the surface area of the second top-fin panel. In an embodiment, the surface area of the first sub-region covers at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 99.5% of the surface area of the second top-fin panel.

[0019] In an embodiment, the surface area of the first sub-region covers 100% of the surface area of the second top-fin panel. In an embodiment, the first sub-region covers the full second top-fin panel.

[0020] In an embodiment, the first top-fin panel may comprise a second sub-region and the third top-fin panel may comprise a third sub-region, in which second and third subregions the inside heat sealable layer have been treated to reduce their sealing strength, which second sub-region and third sub-region are configured to be folded onto a first and second sub-sub regions, respectively, of the second sub-region when the container is produced from the blank.

[0021] In an embodiment, the treatment of the heat sealable layer on the second sub-region and / or the third sub-region may be the addition of a layer of an adhesive material comprising a thermosealable matrix and a dispersed phase.

[0022] In an embodiment, the first sub-region tapers towards the gable crease line providing a localised narrowing of the second sub-region straddling the gable crease line.

[0023] The second top-fin panel may comprise a second sub-region in which the inside heat sealable layer has not been treated to reduce its sealing strength, the second sub-region enclosing the first sub-region.

[0024] In an embodiment, the dispersed phase may be polybutene-1, polypropylene co-polymer, a styrene acrylate co-polymer or a blend thereof.

[0025] In an embodiment, the thermosealable matrix may comprise a polyolefin, and the polyolefin is heat sealable with the inside heat sealable layer.

[0026] In an embodiment, the thermosealable matrix may comprise a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a metallocene linear low density polyethylene (mLLDPE), a medium density polyethylene (MDPE), a high density polyethylene (HDPE), a polypropylene (PP) or any blend thereof, preferably a LDPE, a LLDPE or a mLLDPE.

[0027] In an embodiment, the adhesive properties of the second top-fin panel, the second subregion and / or the third sub-region provides a force in the range of 20 to 60N for opening the gable top. This may be measured by a tensile testing instrument, such as an Instron 5943. This force may be measured according to ISO 17480:2015.

[0028] In detail, the opening performance of a gable top carton can be evaluated by a tensile testing instrument like Instron 5943 according principle described in ISO 17480:2015. As described by this method the peeling force required to open a Gable Top carton is measured. The force may be measured at a speed of 100 mm / min. The equipment can be used for formed cartons with different configuration and cross section. In order to perform the mechanical test, it is recommended to test 10 filled cartons for each variant. When opening a carton make sure to separate the top fin panel sections 182a and 182b and push the flaps backwards and make sure that the flaps are folded completely back on to the gable roof. Start the Instron 5943 apparatus and calibrate said apparatus according to standard procedures according to Instron 5943. Jog the equipment and ensure that there is a slack in the wire, press down the opening lever. Place the carton to be tested on the testing unit. Push down the spout area to ensure contact with the opening lever and the spout area. Start the measuring procedure. The opening lever will open the carton and the spout is formed. Evaluate the quality of the pouring area as to possible board splitting and fiber tear.

[0029] In an embodiment, the adhesive properties of the second top-fin panel, the second subregion and / or the third sub-region provides a force in the range of 25 to 50N, or 30 to 40N for opening the gable top.

[0030] According to a second aspect, the present disclosure provides a packaging container for holding a pourable product, the container comprising a packaging container blank according to the first aspect of the invention.

[0031] In an embodiment, the force required for opening the gable top is less than for the force required for opening the gable top not comprising the adhesive layer, i.e. for a container where the inside heat sealable layer is directly sealed to itself. According to a third aspect, the present disclosure provides a method of producing a gable-top paper or paperboard based packaging container, comprising the steps of

[0032] - providing a laminate paper or paperboard packaging material blank comprising an inside heat sealable layer and a plurality of top-closure sub-panels, comprising: a first top-closure sub-panel comprising a first top-fin panel; a second top-closure sub-panel neighbouring the first top-closure subpanel and comprising a second top-fin panel; and a third top-closure sub-panel neighbouring the second top-closure subpanel and comprising a third top-fin panel, the second top-fin panel comprising a gable crease line extending across the second top-fin panel between a top edge of the second top-closure sub-panel and a top-fin crease line of the second top-closure sub-panel, which gable crease line partitions the top-fin panel into a first top-fin panel section and a second top-fin panel section; the second top-fin panel comprising a first sub-region extending transversally across the blank crossing the gable crease line, - reducing the sealing strength of the inside heat sealable layer in the first sub-region of the second top-fin panel by adding a layer of an adhesive material comprising a thermosealable matrix and a dispersed phase;

[0033] - folding the blank bringing the first top-fin panel section into contact with the first topfin panel and the second top-fin panel section into contact with the third top-fin panel; and

[0034] - top-sealing the blank by sealingly attaching the first top-fin panel section with the first top-fin panel and the second top-fin panel section with the third top-fin panel.

[0035] Said step of reducing the sealing strength of the inside heat sealable layer may not fully eliminate the sealing strength of the inside heat sealable layer, i.e. may not fully inhibit or prevent the inside heat sealable layers from forming a seal with adjoining panel sections.

[0036] By adding controlling the type and amount of the dispersed phase the strength of the seal obtained by the top-sealing step is controlled, which in turns allows to get a controlled cohesive failure in the formed seal and avoid fibre tear in the paperboard layer of the laminated structure.

[0037] The printed layer may comprise a grammage or base weight of the anti-sealing material within the range of 0.2 to 10.0 g / m2, of 0.5 to 8.0 g / m2, or of 1.0 to 5.0 g / m2.

[0038] Short description of the drawings

[0039] In the following description this invention will be further explained by way of exemplary embodiments shown in the drawings:

[0040] Fig. l is a top view of an outside surface of a prior art.

[0041] Fig. 2 is a detailed top view of an inside surface of the blank according to Fig. 1.

[0042] Fig. 3 is a schematic cut-through view of a laminate packaging material.

[0043] Fig. 4 schematically illustrates a closed gable-top packaging container.

[0044] Fig. 5 schematically illustrates a semi-open gable-top packaging container.

[0045] Fig. 6 schematically illustrates an open gable-top packaging container.

[0046] Figs. 7-9 illustrate a first embodiment of a blank according to the present invention.

[0047] Fig. 10 illustrates a second embodiment of a blank according to the present invention.

[0048] Figs. 11 and 12 illustrate a third embodiment of a blank according to the present invention.

[0049] Fig. 13 illustrates a fourth embodiment of a blank according to the present invention.

[0050] Figs. 14 illustrates a fifth embodiment of a blank according to the present invention.

[0051] It should be understood that the drawings are not intended to limit the invention to the subjectmatter depicted in the drawings.

[0052] In the drawings, like reference numerals have been used to indicate common parts, elements or features unless otherwise explicitly stated or implicitly understood by the context.

[0053] Detailed description

[0054] In the following, specific embodiments of a blank and a container produced therefrom will be described in more detail with reference to the drawings. However, it is specifically intended that the invention as defined in the following claims is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the claims.

[0055] An embodiment of a prior art blank 100 is disclosed in Figs. 1 and 2. The blank 100 is disclosed with the surface configured to form the outside surface of the container facing the viewer.

[0056] The blank 100 is made from a multi-ply paper or paperboard sheet on which is laminated one or a plurality of barrier layers for holding a pourable product, e.g. a liquid, and / or prevent migration of air and flavour degrading substances through the sheet.

[0057] The blank 100 is generally rectangular and comprises a first, bottom edge 101, a second, top edge 103 and parallel, third and second, side edges 105, 107. The side edges 105 and 107 are generally rectilinear and parallel, whereas the top and bottom edges 101 and 103 have an irregular shape. The blank 100 also comprises a plurality of crease lines defining folding lines along which the blank 100 is configured to be folded when formed into the carton.

[0058] The blank 100 comprises five panels, P1-P5, partitioned by longitudinal crease lines 102, 104, 106 and 108 defining folding lines extending across the panel 100 from the bottom edge 101 to the top edge 103. In the present embodiment, the longitudinal crease lines 102, 104, 106 and 108 are generally rectilinear, parallel and continuous, i.e. uninterrupted, and, consequently, extend longitudinally, i.e. vertically in Fig. 1, across the blank 100 between the bottom edge 101 and the top edge 103.

[0059] Each panel P1-P5 comprises a first sub-panel 110, 112, 114, 116, 118 forming a bottom-closure sub-panel, a second sub-panel 120, 122, 124, 126, 128 forming a wall section sub-panel, and a third sub-panel 130, 132, 134, 136, 138 forming a top-closure sub-panel. The bottom closure sub-panels 110, 112, 114, 116 and 118 are configured to form a bottom closure of the container, and the top-closure sub-panels 130, 132, 134, 136, 138 a top closure of the container. The fifth panel P5 is configured to be attached to an inside surface of the first panel Pl adjacent the side edge 105 when the container is formed.

[0060] First transversal crease lines 140-148 partition the bottom-closure sub-panels 110-118 from the wall section sub-panels 120-128. The crease lines 140-148 are generally aligned, i.e. arranged one after the other, and extend generally transversally across the blank 100. Likewise, second transversal crease lines 150-158 partition the wall section sub-panels 120-128 from the topclosure sub-panels 130-138, are generally aligned and extend generally transversally across the blank 100. Top-fin crease lines 160-168 extend generally transversally across the blank 100 partitioning sub-sub panels 180-188 of the top-closure sub-panels 130-138 from sub-sub-panels 170-178. Sub-sub panels 180-188 form top-fin panels, or seal lips, of the blank, sub-sub-panels 170 and 174 form roof panels, and sub-sub-panels 172 and 176 form gusset panels.

[0061] Gusset panels 172 and 176 each comprises top diagonal crease lines 173a, 173b and 177a, 177b, respectively, partitioning the gusset panel 172, 176 into gusset panel sections 172a- 172c and 176a-176c, respectively.

[0062] Top fin panels 182 and 186 each form a gable seal area and comprises a gable crease line 183 and 187, respectively, partitioning the top fin panel 182, 186 into gable seal area sections 182a and 182b, and 186a and 186b, respectively.

[0063] Diagonal crease lines 173a and 173b intersect with gable crease line 183 and top-fin crease line 162 in a star-like point of intersection 193 (see Fig. 1). Likewise, diagonal crease lines 177a and 177b intersect with gable crease line 187 and top-fin crease line 166 in a star-like point of intersection 195. These points of crease line intersection are sometimes referred to as "starpoints".

[0064] Fig. 2 shows the inside surface of the top-closure region of the blank 100, where the same crease lines, sub-panels and panel sections are indicated by corresponding reference numerals.

[0065] Fig. 3 shows a schematic cross-sectional view of an example of a packaging laminate 200 from which the above-discussed blank 100 may be made.

[0066] The packaging laminate 200 comprises a bulk layer 202 of paper or paperboard or other cellulose-based material. The bulk layer 202 may be a multi -ply bulk layer, i.e. may comprise a plurality of sub-layers having different characteristics (e.g. having different bulk, different fibre composition etc.). The bulk layer 202 may be any material layer providing dimensional stability and direct or indirect stiffness to the packaging laminate 200, such as preferably a paperboard or carton or other cellulose-based material and may specifically be of a liquid paperboard quality (i.e. such as used for liquid food packages, aseptic liquid food packages and retortable food packages).

[0067] The packaging laminate 200 in Fig 3 is oriented in a position in which all illustrated layers above the bulk layer 202 are intended to be turned to face outwards, while, correspondingly, all illustrated layers beneath the bulk layer 202 are intended to be turned to face inwards in a packaging container produced from the packaging laminate 200. In other words, the layers above the bulk layer 202 will form the outside of the finished packaging container, while the layers beneath the bulk layer 202 will form the inside of the packaging container, at the same time as the bulk layer 202 constitutes a central layer in the walls, bottom and top of the packaging container. In order to facilitate an understanding of the present invention, the expressions "inside" and "outside" will hereafter be employed taking as the point of departure the central bulk layer 202. On the inside of the bulk layer 202, the packaging laminate 200 may comprise a barrier layer 204 arranged to prevent migration of oxygen and / or flavour degrading substances through the packaging laminate 200. The barrier layer 204 may be laminated to the inside bulk layer 202 and may be adhered to the bulk layer 202 by any method and / or adhesive known in the art. For example, the barrier layer 204 may be laminated to the bulk layer through an intermediate lamination layer (not shown). The barrier layer 204 may comprise an aluminium foil, polyamide and EVOH barrier layers, vapour deposited and / or metallised films, etc. The intermediate lamination layer may be a thermoplastic material or polymer, such as a polyolefin, preferably low-density polyethylene, LDPE, but could also be another polyolefin, such as polypropylene (suitable for retortable packages), or other thermoplastic polymers, such as carboxylic-group modified polyolefins, such as EAA or EMAA.

[0068] Depending on the content to be held by the packaging container, the barrier layer 204 may be omitted.

[0069] The packaging laminate 200 comprises an inner heat sealable layer 206. The heat sealable layer 206 serves a purpose of protecting the laminated structure, and in particular the bulk layer 202 and the cellulose fibres therein, from moisture originating from inside of the packaging container. If a barrier layer 204 is present, the heat sealable layer 206 may be laminated to the same. If a barrier layer is omitted, the heat sealable layer 206 may be laminated or otherwise adhered to the inside of the bulk layer 202.

[0070] The packaging laminate 200 also comprises an outer heat sealable layer 208. As the inner heat sealable layer 206, the outer heat sealable layer 208 serves a purpose of protecting the laminated structure, and in particular the bulk layer 202 and the cellulose fibres therein, from moisture - in this case from moisture originating from outside the packaging container. The outer heat sealable layer 208 may be laminated to the outside of the bulk layer 202.

[0071] The inner heat sealable layer 206 and the outer heat sealable layer 208 may be made from a thermoplastic polymer, e.g. a polyolefin, such as a polyethylene selected from LDPE (low- density polyethylene), LLDPE (linear low-density polyethylene), mLLDPE (metallocene low- density polyethylene) and blends of any thereof. Alternatively, the heat sealable layers 206 and 208 may be made from a heat sealable polypropylene homo- or copolymer, e.g. suitable for retortable packages.

[0072] Since the inner heat sealable layer 206 and the outer heat sealable layer 208 have as a purpose to protect the bulk layer 202 from moisture, each layer 206 and 208 should preferably cover inside and outside areas of the packaging laminate 200 that may be subjected to moisture. Advantageously, the layers 206 and 208 cover the whole inside and outside areas, respectively, of the packaging laminate 200.

[0073] On sections of the packaging laminate 200 forming visible portions of the packaging container - typically the wall section sub-panels 120-126 and the top-closure sub-panels 130 and 134 (see Fig. 1) - the packaging laminate 200 may comprise a decor layer 210, for example a decorative colour print, such as a printed colour pattern, optionally including text, nouns, marketing brands, logos etc. The decor layer 210 may be printed, e.g. using flexographic techniques, on the outside of the outer heat sealable layer 208. The decor layer 210 may be produced using a halftone reprographic technique where continuous-tone imagery is simulated through the use of dots of ink, varying either in size or in spacing, thus generating a gradient-like effect. Where continuous-tone imagery contains an infinite range of colours or greys, the halftone process reduces visual reproductions to an image that is printed with only one colour of ink, in dots of differing size (pulse-width modulation) or spacing (frequency modulation) or both. Colour printing can be produced by repeating the halftone process for each subtractive colour, e.g. using the CMYK colour model.

[0074] As an example, the decor layer 210 may be laid down onto sections of the packaging laminate 200 forming visible portions of the packaging container using flexographic printing and UV cured inks (UV-flexo inks).

[0075] As is known in the art, the inner heat sealable layer 206 and the outer heat sealable layer 208 also have as a purpose to form seals when a packaging container is produced from the blank. The packaging container is normally produced from the blank in a filling machine by folding the fifth panel P5 to the first panel Pl and sealing the panels Pl and P5 in a longitudinal seam, e.g. by heat sealing the outer heat sealable layer of panel P5 to a corresponding section of the inner heat sealable layer of panel Pl, thus creating a tubular sleeve. Thereafter, the sleeve is bottom-sealed by folding and sealing the bottom-closure sub-panels 110-118, thus creating an open-top proto-container. Thereafter the pourable product to be held by the container is filled into the proto-container through the open top and, finally, the top-closure sub-panels 130-138 are folded and sealed to each other.

[0076] As is known in the art, top sealing the proto container generally involves bringing the top-fin panels 180, 182, 184, 186 andl88 into contact with each other and pressing and heating the topfin panels to thereby heat seal adjoining heat sealable layers of the top-fin panels. In particular, top sealing the proto container generally involves bringing the inside surfaces of top-fin panel sections 186a and 182b into contact with the inside surface of top-fin panel 184 (see Fig. 2) and heat sealing adjoining sections of the inner heat sealable layers of the top-fin panel 184 and the top-fin panel sections 186a and 182b, and, correspondingly, bringing the inside surfaces of topfin panel sections 182a and 186b into contact with the inside surface of top-fin panel 180 (and the inside surface of interposed top-fin panel 188) and heat sealing adjoining sections of the inner heat sealable layers of top-fin panel 180 (and interposed top-fin panel 188) and top-fin panel sections 182a and 186b.

[0077] Furthermore, top sealing involves bringing the outside surfaces of top-fin panel sections 182a and 182b into contact with each other (see Fig. 1) and heat sealing adjoining sections of the outer heat sealable layers of the top-fin panel sections 182a and 182b, and, correspondingly, bringing the outside surfaces of top-fin panel sections 186a and 186b into contact with each other and heat sealing adjoining sections of the outer heat sealable layers of the top-fin panel sections 186a and 186b. Said top-fin panels and panel sections, when brought into contact with each other, form a top fin and top sealing may be effectuated by pressing and heating the top fin in a suitable pressing and heating tool, e.g. using induction heating or ultra-sound. Fig. 4 is a perspective view of a top-sealed packaging container 300 formed accordingly, comprising a gable closure 302 and a sealed top fin 304.

[0078] As far as sealing integrity is concerned, particular care must be taken to provide efficient sealing along the gable crease lines 183, 187, in particular in aseptic containers, e.g. containers intended for holding UHT products. In the sealed container, the gable crease lines 183, 187 extend from the outside of the container to the inside. Consequently, unless efficiently sealed, crease lines 183 and 187 may provide a path for pollutants to contaminate the product inside the container, thus compromising shelf-life. In order to increase sealing efficiency, it is known to provide panels P2 and P4 as so called "pointed panels", i.e. panels where the lateral extent of the topfin panels 812 and 184 is greatest in the area of the gable crease lines 183, 187. This will extend the length of the crease lines 183, 187 and, consequently, allow a larger sealed area than otherwise would have been possible. In the blanks disclosed in Figs. 1 and 2, panels P2 and P4 are "pointed panels" as is evidenced by the top edge 103 in panels P2 and P4 not being rectilinear but forming an obtuse angle at the point of intersection with the gable crease line 183 and 187, respectively. However, having a larger sealed area will also make it more difficult to open the packaging container.

[0079] With reference to Figs. 5 and 6, opening the packaging container 300 generally involves a first step of breaking the seal formed between the outside surfaces of top-fin panel sections 182a and 182b (see Figs. 1 and 5) and a subsequent, second step of breaking the seals formed between the inside surfaces of top-fin panel 184 and top-fin panel section 182b, and between the inside surfaces of top-fin panel 180 and top-fin panel section 182a, respectively (see Figs. 2 and 6).

[0080] The top-fin panel sections 182a and 182b are congruent, i.e. they are identical in size and shape. Consequently, when the packaging container 300 is in a closed position, the top-fin panel sections 182a and 182b abut one another in a contact region which generally corresponds to the region of the top-fin panel section 182a and 182b, respectively.

[0081] In the open position of the packaging container 300 the top-closure sub-panel 132 (see Fig. 1) forms a pouring spout 306 (see Fig. 6). In particular, the inside surfaces of top-fin panel sections 182a and 182b form pouring lips of the pouring spout 306. Gable crease line 183 (see Fig. 2) forms a pouring spout chute 310, i.e. a bottom of the pouring spout 306, when the container 300 is in an open position.

[0082] Figs. 7-9 illustrate an embodiment of a blank 100' according to the present invention. The blank 100' generally corresponds to the blank 100 disclosed in Figs. 1 and 2, but blank 100' has additionally been treated to reduce the opening force required in the above-discussed second step of opening the container. In the blank 100a, the top-fin panel 182 comprises a sub-region 72 in which the inside heat sealable layer 206 has been treated to reduce its sealing capacity by adding a layer of an adhesive material comprising a thermosealable matrix and a dispersed phase. In other words, in sub-region 72 the ability of the inside heat sealable layer 206 to form a seal with adjoining panel sections is reduced, but not completely inhibited. By using this material, the sealed top fin 304 still has a strong enough sealing so that the container does not leak, while reducing the strength of the seal enough to ensure an easier opening. Top-fin panels 180 and 184 comprise corresponding sub-regions 70 and 74.

[0083] In addition, sub-region 72, the adhesive material ensures an easier opening and avoids fiber tear between inner heat sealable layer 206 and the the bulk layer 202 and the cellulose fibres therein.

[0084] Fiber tear may cause splitting of the bulk layer 202 and result in a poor pouring performance of the liquid product.

[0085] Adding a dispersed phase in the thermosealable matrix create a cohesive failure inside the seal after the top sealing step. The required force to open the container is lower than if the adhesive layer was not present, and can be low enough so that fiber tear between inner heat sealable layer 206 and the the bulk layer 202 and the cellulose fibres therein can be avoided. Sub-region 72 comprises a first and a second sub-sub regions 72a and 72b, which are partitioned by the gable crease line 183. Sub-sub regions 72a and 72b are mirror images of one another but otherwise congruent. In other words, the first and second sub-sub regions 72a and 72b are mirror- symmetric about the gable crease line 183.

[0086] Sub-region 70 is generally a mirror image of sub-sub region 72a about the crease line 102. Likewise, sub-region 74 is generally a mirror image of sub-sub region 72b about the crease line 104. Consequently, when the blank 100a is folded to form a packaging container, sub-region 20 will be folded onto sub-sub region 72a and sub-region 74 will be folded onto sub-sub region 72b.

[0087] As can be most clearly seem in Fig. 8, sub-region 72 is surrounded by a second, un-treated subregion 82 of the top-fin panel 182, in which second sub-region 82 the sealing strength of the inside heat sealable layer 206 is left unaffected. In other words, in sub-region 82 the sealing strength of the inside heat sealable layer 206 is not reduced or inhibited.

[0088] Consequently, when a container made from the blank 100a is top-sealed, the inside surface 206 of the top-fin panel 182 will form a "normal" seal with the inside surface 206 of top-fin panels 180 and 184, respectively, only in sub-region 82. In the interface between sub-region 72 and sub-regions 70 and 74, respectively, the strength of the seal will be reduced, thus facilitating the above-discussed second opening step.

[0089] Contrary to a treatment of sub-regions 70. 72 and 74, where the sealing would be completely inhibited, i.e. where the inside layer 206 would be prevented from creating a seal altogether; the current embodiment ensures that the seal top fin does not leak. In the transversal direction of the blank 100a, the sub-region 82 extends continuously along the top edge 103 and also along the crease line 162, thus forming a first uninterrupted sub-sub region or band 82a along the top edge 103 and a second uninterrupted sub-sub region or band 82b along the crease line 162. Also, on either side of sub-region 72, sub-region 82 comprises sub-sub regions 82c and 82d. Consequently, when a container made from the blank 100a is topsealed, the interfaces between sub-region 72 and sub-regions 70 and 74, respectively, will form an internal region or layer completely surrounded by a hermetically sealed boarder, in which internal region there is a weakened seal between the inside layers 206.

[0090] As is most clearly illustrated in Fig.8, the sub-region 72 comprises a first, substantially rectilinear, lower boundary line 76a running substantially parallel to the top-fin crease line 162. The sub-region 72 further comprises second and third substantially rectilinear boundary lines 76b and 76c, forming sides of the sub-region 72, running at an angle of approximately 45 degrees to the crease lines 102 and 104, respectively.7 Also, the sub-region 72 comprises a fourth, upper boundary line 76d running substantially parallel to the top edge 103.

[0091] However, in a region straddling the gable crease line 183, the upper boundary line 76d deviates towards and approaches the lower boundary line 76a, thus creating a narrowing or waist where the lateral distance between the boundary lines 76a and 76d is reduced. In other words, in the transverse direction of the blank 100', the sub-region 72 displays a taper or narrowing centred around the gable crease line 183. In the disclosed embodiment, the taper or narrowing is defined by substantially rectilinear boundary line segments 76d-l, 76d-2 and 76d-3, where segment 76d-2 runs parallel to boundary line 76a and segments 76d-l and 76d-3 run substantially parallel to boundary line 76b and 76c, respectively.

[0092] As a consequence of this taper or narrowing, the container produced from the blank 100a will comprise, when sealed, a plug-like sealed region extending from the top edge 103 and down into the top fin along the gable crease line 183, which plug-like region is restricted by boundary line segments 76d-l, 76d-2 and 76d-3.

[0093] Consequently, a container made from the blank 100a will, when in a sealed state, comprise, along the gable crease line 183, a first section SI and a second section S2 where the top-fin 182 is hot-sealed to the neighbouring top-fin panels 180 and 184, and a third section S3, which is intermediate the first section SI and the second section S2, where the sealing strength between the top-fin panel 182 and the top-fin panels 180 and 184 is reduced. It has been found that this configuration provides a seal fulfilling aseptic requirements while at the same time being easy to open.

[0094] In the disclosed embodiment, the length of SI is approximately 4 mm, the length of S2 approximately 1.5 mm and the length of S3 approximately 5.5 mm. Consequently, the length of the gable crease line 183, corresponding to the height of the top fin, is approximately 11 mm. The distance dl between the upper boundary line 76d and the top edge 103 is approximately 2 mm (see Fig. 8) and the distance d2 between the side boundary lines 76b and 76c and the crease lines 102 and 104, respectively, is approximately 5 mm. According to one embodiment, said treatment of the sub-regions 70, 72 and 74 comprises coating the inside heat-sealable layer 206 of the sub-regions 70, 72 and 74 with a layer of material weakening the seal between the inside heat sealable layers 206 and adjoining panel sections. In the following, such a layer will be referred to as a peelable seal layer. The peelable seal layer prevents fiber tear between inner heat sealable layer 206 and the the bulk layer 202 and the cellulose fibres therein (for example between a PE layer and a board layer) resulting in a clean split between the layers.

[0095] Here the term peelable seal layer is to be understood as a sealing layer that is generally weaker than traditional sealing layers, in order to facilitate the opening, the peelable seal layer is still strong enough to ensure that the container is hermetically sealed and does not open by itself, i.e. unless the user desires to open the container.

[0096] Said coating may comprise printing a layer of weak-sealing material comprising a thermosealable matrix and a dispersed phase onto the sub-regions 70, 72, 74, e.g. utilising a flexographic printing technique. The thermosealable matrix may be made from any material that may be heat-sealed with the material of the adjoining section. Preferably, the thermosealable matrix may comprise a polyolefin, more preferably the thermosealable matrix may comprise a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a metallocene linear low density polyethylene (mLLDPE), a medium density polyethylene (MDPE), a high density polyethylene (HDPE), a polypropylene (PP), a polyalphaolefin (PAO), an ethylene propylene copolymer or any blend thereof; even more preferably the thermosealable matrix may comprise a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a metallocene linear low density polyethylene (mLLDPE). The dispersed phase may be any dispersed phase that reduces the strength of or weakens the sealing between the material of the adjoining section, in other words that makes it easier to separate the sealed surfaces after sealing. In particular, the dispersed phase may be made of polybutene-1, polypropylene copolymer, an ethylene propylene copolymer or a styrene acrylate co-polymer.

[0097] The weak-sealing material may be deposited by an anilox roller.

[0098] The grammage or base weight of the weak-sealing material deposited by the anilox roller may be within the range of 0.2 to 0.8 g / m2, e.g. within the range of 0.4 to 0.5 g / m2.

[0099] In the transversal direction of the blank 100a, the sub-region 82 extends continuously along the top edge 103 and also along the crease line 162, thus forming first uninterrupted sub-sub region or band 82a along the top edge 103 and a second uninterrupted sub-sub region or band 82b along the crease line 162. Also, on either side of sub-region 72, sub-region 82 comprises subsub regions 82c and 82d. Consequently, when a container made from the blank 100a is topsealed, the interface sub-region 72 will be enclosed by a hot-seal formed between the top-fin panel 182 and top-fin panels 180 and 184, respectively, said hot-seal being stronger than in the sub -region 72. Fig. 10 illustrates another embodiment of a blank 100b according to the present invention. The blank 100b corresponds to the blank 100a disclosed in Figs. 7-9, but in blank 100b sub-regions 70 and 74 have been omitted. Consequently, in blank 100b the reduction or elimination of the sealing strength of the inner heat-sealable layer is provided solely by sub-region 72. The mechanisms reducing the opening force required in the above-discussed second step is otherwise the same as previously discussed.

[0100] Figs. 11 and 12 illustrate another embodiment of a blank 100c according to the present invention. The blank 100c corresponds to the blank 100a disclosed in Figs. 7-9, except in blank 100c the narrowing of the sub-region 72 in the region of the gable crease line 183 is provided by boundary lines 76d-l and 76d-3 meeting at a right angle on the gable crease line 183. Consequently, as compared to the embodiment disclosed in Figs. 7-9, the waist of the subregion 72 will be narrower and the plug-like seal will be V-shaped.

[0101] In the embodiment disclosed in Figs. 11 and 12, the length of SI is approximately 7 mm, the length of S2 approximately 1.5 mm and the length of S3 approximately 2.5 mm.

[0102] Fig. 13 illustrate a further embodiment of a blank lOOd according to the present invention. The blank lOOd corresponds to the blank 100b disclosed in Figs. 10, except in blank lOOd, the subregion 72 covers the full second top-fin panel 182.

[0103] Fig. 14 illustrate a further embodiment of a blank lOOe according to the present invention. The blank lOOe corresponds to the blank 100a disclosed in Figs. 7-9, except in blank lOOe, the subregion 72 covers the full second top-fin panel 182.

[0104] Sub-region 70 is generally a mirror image of sub-sub region 72a about the crease line 102. Likewise, sub-region 74 is generally a mirror image of sub-sub region 72b about the crease line 104.

[0105] However, it is not a requirement that sub-regions 70 and 72a as well as 74 and 74b are mirror images.

[0106] In another embodiment, not illustrated here, the totality of the surface of the first, second, third top-fin panel 180, 182, 184 and optionally of the fourth top fin panel 186 of the blank 100 are covered with a peelable seal layer. This is particularly advantageous as this allows for the full opening of the gable top arrangement. Opening the gable top fully allows for better access to the content of the container, which allows to better empty the container when in use. This is particularly relevant for application with thicker contents, such as home care products, yogurt and cream.

[0107] It is appreciated that certain features of the invention, which, for clarity, have been described above in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which, for brevity, have been described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

[0108] In the preceding description, various aspects of the blank and container according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, may lie within the scope of the present invention as defined by the following claims.

Claims

CLAIMSCLAIMS1. A packaging container (300) blank (100) made from a laminate packaging material (200) comprising an inside heat sealable layer (206) and comprising a plurality of top-closure sub-panels (130, 132, 134, 136, 138), the blank (100) comprising: a first top-closure sub-panel (130) comprising a first top-fin panel (180); a second top-closure sub-panel (132) neighbouring the first top-closure sub-panel (130) and comprising a second top-fin panel (182); and a third top-closure sub-panel (134) neighbouring the second top-closure sub-panel (132) and comprising a third top-fin panel (184), the second top-fin panel (182) comprising a gable crease line (183) extending across the second top-fin panel (182) between a top edge (103) of the second topclosure sub-panel (132) and a top-fin crease line (162) of the second top-closure sub-panel (132), which gable crease line (183) partitions the top-fin panel (182) into a first top-fin panel section (182a) and a second top-fin panel section (182b); the first top-fin panel section (182a) being configured to be sealingly attached to the first top-fin panel (180) during top-sealing of the container (300); the second top-fin panel section (182b) being configured to be sealingly attached to the third top-fin panel (184) during top-sealing of the container (300); and the first top-fin panel section (182a) and the second top-fin panel section (182b) being configured to be separated from the first top-fin panel (180) and the third top-fin panel (184), respectively, during opening of the container, providing a pouring spout, characterised by the second top-fin panel (182) comprising a first sub-region (72) extending transversally across the blank (100) crossing the gable crease line (183), in which first sub-region (72) the inside heat sealable layer (206) has been treated to reduce its sealing strength; wherein the treatment of the first sub-region (72) on the second top-fin panel (182) is the addition of a layer of an adhesive material comprising a thermosealable matrix and a dispersed phase; wherein the dispersed phase is polybutene-1, polypropylene co-polymer, a styrene acrylate co-polymer or a blend thereof.

2. A packaging container blank (100) according to claim 1, wherein the surface area of the first sub-region (72) covers at least 80% of the surface area of the second top-fin panel (182).

3. A packaging container blank (100) according to claim 1 or 2, wherein the first sub-region (72) covers the full second top-fin panel (182).

4. A packaging container blank (100) according to any one of the previous claims, characterised by the first top-fin panel (180) comprising a second sub-region (70) and the third top-fin panel (184) comprising a third sub-region (74), in which second and third sub-regions (70, 74) the inside heat sealable layer (206) have been treated to reduce their sealing strength, wherein the first sub-region (72) is partitioned by the gable crease line (183) into a first sub-sub region (72a) and a second sub-sub region (72b), the first and second sub-sub regions (72a, 72b) being mirror-symmetric about the gable crease line (183) which second sub-region (70) and third sub-region (74) is configured to be folded onto the first and second sub-sub region (72a) and (72b), respectively, when the container (300) is produced from the blank (100).

5. A packaging container blank (100) according to claim 4, wherein the treatment of the heat sealable layer (206) on the second sub-region (70) and / or the third sub-region (74) is the addition of a layer of an adhesive material comprising a thermosealable matrix and a dispersed phase.

6. A packaging container blank (100) according to any one of the previous claims, wherein the first sub-region (72) tapers towards the gable crease line (183) providing a localised narrowing (78) of the first sub-region (72) straddling the gable crease line (186).

7. A packaging container blank (100) according to any one of the previous claims, wherein the thermosealable matrix comprises a polyolefin, and is heat sealable with the inside heat sealable layer (206).

8. A packaging container blank (100) according to any one of the previous claims, wherein the thermosealable matrix comprises a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a metallocene linear low density polyethylene (mLLDPE), a medium density polyethylene (MDPE), a high density polyethylene (HDPE), a polypropylene (PP) or any blend thereof, preferably a LDPE, a LLDPE or a mLLDPE.

9. A packaging container blank (100) according to any one of the previous claims, wherein the adhesive properties of the second top-fin panel (182), the second sub-region (70) and / or the third sub-region (74) are in the range of 20 to 60 N, measured by a tensile testing instrument, according to ISO 17480:2015.

10. A container (1) for holding a pourable product, the container (1) comprising a packaging container blank (200) according to any one of the previous claims.

11. A method of producing a gable-top paper or paperboard based packaging container (300), comprising the steps of:- providing a laminate paper or paperboard packaging material (200) blank (100) comprising an inside heat sealable layer (206) and a plurality of top-closure subpanels (130, 132, 134, 136, 138), comprising: a first top-closure sub-panel (130) comprising a first top-fin panel (180); a second top-closure sub-panel (132) neighbouring the first top-closure sub-panel (130) and comprising a second top-fin panel (182); and a third top-closure sub-panel (134) neighbouring the second top-closure sub-panel (132) and comprising a third top-fin panel (184), the second top-fin panel (182) comprising a gable crease line (183) extending across the second top-fin panel (182) between a top edge (103) of the second top-closure sub-panel (132) and a top-fin crease line (162) of the second top-closure sub-panel (132), which gable crease line (183) partitions the top-fin panel (182) into a first topfin panel section (182a) and a second top-fin panel section (182b); the second top-fin panel (182) comprising a first sub-region (72) extending transversally across the blank (100) crossing the gable crease line (183),- reducing the sealing strength of the inside heat sealable layer (206) in the first subregion (72) of the second top-fin panel (182) by adding a layer of an adhesive material comprising a thermosealable matrix and a dispersed phase; wherein the dispersed phase is polybutene-1, polypropylene co-polymer, a styrene acrylate co-polymer or a blend thereof;- folding the blank (100) bringing the first top-fin panel section (182a) into contact with the first top-fin panel (180) and the second top-fin panel section (182b) into contact with the third top-fin panel (184); and- top-sealing the blank (100) by sealingly attaching the first top-fin panel section (182a) with the first top-fin panel (180) and the second top-fin panel section (182b) with the third top-fin panel (184).

12. The method according to claim 11, wherein the layer of adhesive material comprises a grammage of the material within the range of 0.2 to 10.0 g / m2.

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